From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Carburetter performance, focusing on air/petrol velocity and mixture richness in the New Phantom model.
| Identifier | ExFiles\Box 178\1\ img064 | |
| Date | 26th November 1925 | |
| EXPERIMENTAL REPORT. EXPL. No. REF. Hs{Lord Ernest Hives - Chair}/ACL/LG261125 - 3 - than at high speeds. We see that an increase of air velocity from 40 ft/sec. to 80 ft/sec. results in an increase in petrol velocity from .387 ft/sec. to 2.8 ft/sec. which means that the petrol flow has increased 262% more than the air flow and the mixture is therefore 262% rich if no extra air is supplied. An increase of air velocity from 80 ft/sec. to 160 ft/sec. results in a richening up of only 11%. As the air valve is the chief moving part of the carburetter it will be realised that it is one of the most important parts and upon its accurate working depends the correct functioning of the carburetter. When considering the New PhantomCodename for PHANTOM I carburetter it simplifies matters if we treat it as two separate carburetters - one which operates under low depression - to supply the engine demands at low speeds and light running, and the other, together with the first, operates under higher depressions. The low speed throat and jet form the low depression carburetter and the diaphragm functions for this as the extra air valve supplying air for delusion of the richening low speed mixture until such time as the high speed jet comes into operation, when it again becomes necessary to supply air from some other source to compensate for the richening tendency of the high speed jet. This other air is admitted through the air valve ports. CONDITIONS TO BE SATISFIED. We gather from the above that it is very important that (contd). | ||